Bryan Norcross: Tropical Storm Melissa likely to form in the Caribbean

Updated at 9:30 a.m. ET on Monday, Oct. 20, 2025

The odds that the tropical disturbance in the Caribbean will organize and strengthen are now in the high range. The National Hurricane Center is still painting a large potential development zone across much of the Caribbean, indicating uncertainty about where the development will occur. 

The disturbance is already producing winds near 40 mph, so the system is likely to become Tropical Storm Melissa when it organizes a full circulation or soon thereafter.

The upper-level winds are forecast to become conducive to development by later today, and the heat content of the water under the system will increase as it progresses west, which should encourage the system to organize and strengthen.

Around Wednesday, there is a fork in the road. One group of forecasts has the system rapidly turning north or northeast toward Hispaniola – the large mountainous island containing Haiti and the Dominican Republic. This happens because the disturbance quickly organizes into Tropical Storm or Hurricane Melissa, and the storm gets grabbed by a dip in the jet stream and pulled north.

The other scenario is that the system intensifies more slowly, the jet stream dip misses it, and it drifts west or southwest in the Caribbean for days.

All the various computer forecast systems show both possibilities and give odds of each happening. The odds that likely-Melissa will turn north have been increasing, so now they are the favored outcome, although not by a lot.

Residents in Haiti, the Dominican Republic, Puerto Rico and the surrounding islands should plan to monitor the situation this week. The consensus timing shows likely-Melissa approaching Hispaniola on Friday and impacting the island through the weekend.

If development is delayed and the system is not immediately scooped north, it still could strengthen in the Caribbean while it’s drifting west and be pulled north toward Cuba by the next jet stream dip. The rough schedule for that would be early to mid-next week. But that’s a lower-odds scenario.

The only threat to the mainland U.S. could remotely come in the unforecastable future if the storm drifts into the far western Caribbean and swings wide as it gets pulled north. The odds of that happening are extremely low based on what we know now.

Once the system organizes, hopefully, the long-range forecasts will come into more agreement. In the meantime, the threat is to Haiti, the Dominican Republic and, to a lesser degree, Puerto Rico. Stay informed.